Jewelry clasp having two fastening parts and use of said jewelry clasp, bracelet, and kit

ABSTRACT

The invention relates to a jewelry clasp, comprising two fastening parts, which each have, among other things, a permanent magnet. The invention further relates to the use of such a jewelry clasp as a safety closure and/or fastening system, to bracelet comprising such a jewelry clasp, and to a kit comprising at least two bracelets.

The invention relates to a jewelry clasp comprising two cylindricalfastening parts that are designed to be complementary to one another,wherein the jewelry clasp can be closed in a closing position and eachfastening part has a permanent magnet, as well as a housing with barbsand holding devices. These two fastening parts may each be attached inparticular to one of the two ends of a bracelet. In another aspect, theinvention relates to a bracelet comprising a jewelry clasp according tothe invention, as well as a kit comprised of a plurality of bracelets,wherein the bracelets in the kit may have a jewelry clasp according tothe invention.

It is consistent with general everyday experience that it is difficultto place a bracelet on one's own wrist. The reason for this is that thehand around the wrist of which the bracelet is to be fastened is nolonger available to close the fastening of the bracelet.

Various types of bracelet fasteners are known in the prior art. Theseinclude jewelry clasps designed in two parts, one fastening part beingattached to one end of the bracelet and the other fastening part beingattached to the other end of the bracelet. To bring the jewelry claspsinto a closing position, one fastening part will often have ahook-shaped structure which must be introduced in a suitable manner intothe second fastening part to achieve the desired fixation.

One disadvantage of such hook fasteners is that the fastening parts areusually very small and are made of thin materials, which are sometimesprocessed poorly, in order to save on the cost of materials. Inaddition, such hooks do not usually have suitable guides to assist theuser, so that the hook-shaped structure of one fastening part can reachthe receptacle part of the other fastening part in a suitable manner.The handling of such a jewelry clasp from the prior art is thereforedifficult, in particular when the fastener must be closed with just onehand.

It is also possible that the hook-shaped structure becomes stuck orhooked in the wrong position in the receiving structure of the otherfastening part and this gives the user the impression that the jewelryclasp is properly closed. However, then with any movement or pulling onthe fastening parts, it may happen that the fastening is released andthe bracelet falls from the wearer's wrist, whether noticed or not.

There are also known jewelry clasps which are also designed in two partsso that the two fastening parts have an outside thread and an insidethread, so that such a jewelry clasp can be closed by rotating the twofastening parts together. However, everyday experience has taught usthat it is very difficult to close such a rotary fastener in particularwhen only one hand is available, as mentioned above. The reason for thisis that one of the two fastening parts must be secured, while the otherfastening part must be rotated. This is difficult to manage with justone hand.

Another disadvantage of such a rotary fastener is also that it is noteasy under the difficult conditions described above to accurately placethe fastening part with the outside thread in exactly the correctposition with respect to the fastening part with the inside thread, sothat the rotary closure can be closed immediately. Instead, it is oftenthe case that the one fastening part is inserted into the otherfastening part with a certain angle of inclination so that the twofastening parts become engage and it is further made more difficult toclose the jewelry clasp designed as a rotary fastener. Here again withsuch jewelry clasps it is important to be aware that the manufacturingof the two fastening parts that fit together must be carried out with agreat precision and the two threads must not have any manufacturingrelated burrs which would make it more difficult to fasten the partscorrectly.

In addition, jewelry clasps based on magnetic attraction between twomagnets whose different poles are opposite one another are also known inthe prior art. Such fasteners are usually also designed in two parts,where the two fastening parts each comprise a magnet with the magnets ofmutually repellant poles being arranged opposite one another. The use ofmagnets in conjunction with jewelry clasps has the advantage that use ofsuch a jewelry clasp is simplified because the magnetic force actingbetween the two fastening parts facilitates the approach of the twoclosure parts to one another. However, jewelry clasps based only onmagnetic force are easy to open because the magnetic force of thecommercial magnets that are available inexpensively is either limited orvery expensive when using magnetic materials that generate greatermagnetic forces.

Against the background of this prior art, the object of the presentinvention is to provide a jewelry clasp which does not have thedisadvantages and shortcomings of the jewelry clasps described in theprior art while being simple and convenient to open and close with justone hand and ensuring a secure fastening even when there is a suddenpull.

This object is achieved by the features of claim 1. Thus, according tothe invention, a jewelry clasp having two fastening parts is provided,each comprising a permanent magnet and a housing, wherein the housinghas an opening and opposite this there is a rear side such that thehousing comprises a first area that is preferably cylindrical and asecond area wherein the second areas of the fastening parts consist ofbarbs and holding devices designed to be complementary to one another,and wherein the jewelry clasps may be opened and may be closed in aclosing position, such that in the closing position, one barb of afastening pan is introduced into a holding device of the other fasteningpart, and the permanent magnets are in contact with one another.

It is provided in particular that a jewelry clasp has two fasteningparts, such that the fastening parts each comprise a permanent magnetand a housing. The housing has an opening and a rear side opposite thisopening. In addition, the housing has a cylindrical first and secondarea wherein the second area of the fastening parts consists of barbsand holding devices designed to be complementary to one another. Thejewelry clasp may be opened and closed in the closing position, suchthat a barb of a fastening part is introduced into a holding device inthe other fastening part in the closing position, and the permanentmagnets are in contact with one another.

It is also preferable that the fastening parts each have a permanentmagnet and a housing, such that the opening in the housing is opposite arear side of the fastening part and the housing consists of a firstcylindrical area and a second area such that the second area is formedby barbs and holding devices. The jewelry clasp according to theinvention is characterized in that in a closing position of the jewelryclasp, there is one barb of a fastening part in a holding device of theother fastening part and the permanent magnets are in contact with oneanother.

When using the jewelry clasp according to the invention, a mechanicalapproach comprising the barb and holding devices and an approach basedon magnetic force, which effectively facilitates the approach of the twofastening parts to one another, advantageously supplement one another.Due to this special design of the barbs and the holding devices, thereis a magnetic force caused by the two permanent magnets between thefastening parts, bringing the two fastening parts into contact with oneanother, as well as the barbs and the holding devices, so that aparticularly secure fastening of the jewelry clasp is ensured. Thus,through the combination according to the invention of the curved designof the intermediate spaces in the barbs, which are situated in thetransitional area between the first area of the housing and the secondarea of the housing of the fastening parts achieves a synergistic effectwith the attractive effect between the magnets caused by the magneticforce between the permanent magnets, this synergistic effect consistingof the fact that the two fastening parts automatically enter thepreferred closing position due to the magnetic force because of thedesign of the barbs, wherein the closing position is surprisingly securewith regard to unwanted opening of the jewelry clasp. The curved shapeof the intermediate spaces between the barbs is illustrated in FIGS. 2and 5 in particular. It has been found that the synergistic effect goesbeyond what the average person skilled in the art would have expectedfor simple aggregation of a magnetic single fastener and a mechanicalsingle fastener with regard to the strength and safety of the closingeffects of the jewelry clasps according to the invention.

If the barbs of one fastening part pass through the opening in thehousing of the other fastening part into these interspaces, the twofastening parts experience an attractive magnetic force due to thisproximity. This draws the barbs into the interspace until the barbs arein form-fitting contact with the housing wall of the other fasteningpart from which they are moved further in the direction of the holdingdevices until they engage in the latter. Thus the jewelry clasp is in aclosing position and a surprisingly secure closure of the piece ofjewelry is ensured. In particular, the curved design of the fasteningpart interspaces, the barbs and the holding devices as well as themagnetic attractive force supplement one another to yield a surprisinglyeffective closing mechanism. When there is a sudden release of theform-fitting connection of the two permanent magnets, for example, thecorresponding design of the barbs and the holding devices advantageouslycontinues to ensure a secure fastening of the jewelry clasp.

In an advantageous embodiment of the invention, the second areas of thefastening parts comprise sliding surfaces which form an angle α with animaginary axis of opening and closing that runs centrally in thefastening parts. It is preferable for the imaginary opening and closingaxis running centrally in the fastening parts to be arranged centrallyin the first cylindrical area and to extend from there into the secondarea. The term “centrally” in the sense of the present inventionpreferably means that the imaginary opening and closing axis passesthrough the midpoint of the circular base area of the fastening part andis the same distance from all points on the outside wall of thecylinder, such that this distance preferably corresponds to the radiusof the circular base area.

It is additionally preferable for the sliding surfaces to be formed bythe areas that are designed to be flat between the holding device andthe transitional area between the first and second areas of thefastening part. This transitional area preferably correlates with thelowest area of the opening in the housing of the fastening partaccording to the invention. The sliding surfaces are preferably designedto be curved, so that the sliding surfaces of the two fastening parts ofa jewelry clasp according to the invention slide into one another in aparticularly low-friction manner when they encounter one another so thatthe barbs and holding devices of the fastening parts can engage in oneanother and form a surprisingly effective closure that cannot bereleased accidentally. Therefore, an unwanted unintentional release ofthe closure is prevented unexpectedly reliably, when said unwantedunintentional release could result in loss of the piece of jewelry, forexample, if the unwanted opening of the fastening parts of the jewelryclasp is not noticed in time. It was completely surprising that thepresence and design of the sliding surfaces as components of thefastening parts would make the insertion of the barbs into the openingsin the housing particularly simple and would greatly facilitate theestablishment of the closing position.

An imaginary straight line can be drawn into the plane spanned by thesliding surface, the arrangement of this straight line being illustratedwith respect to the sliding surface in FIG. 3. Within the sense of theinvention, it is preferred that the straight line forms an angle α withthe imaginary axis of opening and closing, such that the position ofthis angle in relation to the imaginary axis and the straight line inthe plane of the sliding surface is also shown in FIG. 3.

In another preferred embodiment of the invention, this angle α isgreater than or equal to 25°. It has been found that the fasteningeffect of the jewelry clasp according to the invention leads tosurprisingly good results in this angle range in particular and ensuresa particularly secure connection of the ends of a piece of jewelry thatare to be connected, for example.

The preferred angle size of greater than or equal to 25° in particularcorrelates with the magnetic attractive force of the two magnets of thefastening parts so that the structural design of the jewelry claspcorresponds especially effectively to the magnetic connection betweenthe permanent magnets. Thus a particularly effective unexpectedinteraction between the mechanical closing effect and the magneticclosing effect is achieved. The inventors have discovered in particularthat the combination of magnetic closing effect and mechanical closingeffect leads to a synergistic closing effect of the closure as a wholewhich was not expected by the technical world. Instead it was previouslyassumed according to the prior art that it is sufficient to provideeither a mechanical fastening mechanism or a magnetic fasteningmechanism. However, investigations by the inventors have shown thatprecisely the combination of a magnetic closing effect with a mechanicalclosing effect results in a particularly effective and secure fasteningmechanism, in particular for jewelry, but also for applications in othertechnical fields because the total force and closing effects are greaterthan the sum of the individual fastening mechanisms. This synergisticoverall effect, which exceeds the individual effects, is manifested inparticular when an axial force is applied to the closed jewelry clasp inthe closing position in the direction of the intended axis of openingand closing. A conventional jewelry clasp having only a magneticfastener, for example, could be opened accidentally in this case whenthe axial force exceeds the magnetic fastening force. Such an unintendedopening in the case of an axial pull in the direction of the intendedaxis of opening and closing is rendered practically impossible with thejewelry clasp according to the invention due to the interaction of themagnetic attractive force between the two permanent magnets within thetwo fastening parts and the mechanical fastening mechanism comprised ofbarbs and holding devices.

In another preferred embodiment of the invention, the housing for thefastening parts consists of a first area with a closed exterior wallwherein this first area is connected to the rear side of the fasteningpart. It is additionally preferred for the barbs and holding devices toform the second area of the fastening parts. In the sense of thisinvention, the rear side of the fastening parts is advantageously acircular surface which is facing the piece of jewelry to be closed. Thisrear side forms a base plate for a fastening part. A first area of thefastening part which is cylindrical in design and comprises a closedexterior wall is connected to this base plate.

In the sense of this invention, this first cylindrical area of thejewelry clasp is also referred to as the bottom part. Its height, whenconsidered from the base plate, amounts to approximately one-half theheight of the fastening part. The second area of the fastening part isconnected to the first area of the fastening part and forms the upperarea of the fastening part. This is advantageously formed by barbs andholding devices.

It is preferable for each fastening part to have two barbs and twoholding devices which are opposite one another and in contact with oneanother forming an angular distance of 180° to one another. The barbs ofthe upper area of the fastening part form an extension of the exteriorwall of the lower area of the fastening part. The barbs are shaped likea walking stick. The stick area of the barb is formed by the exteriorwall of the fastening part and preferably has the same thickness as theexterior wall of the lower cylindrical area of the fastening part. Incomparison with a walking stick, the stick area of the barb is designedto be wider and flat.

The upper area of the barb forms a hook-shaped area corresponding to thehandle in the case of a walking stick. The area of the barb where thefingers would be placed in the case of a walking stick corresponds tothe holding device of the upper area of the fastening part. In the frontarea of the handle part of the barb, the thickness of the wall materialbecomes thinner, tapering at the center to a tip shaped like a line.This tip of the barb which is shaped like a line engages in the holdingdevice of the other fastening part when in the closing position.

Between the two barbs of a fastening part there is a curved opening. Theinside of this opening is designed so that in the approach of the twofastening parts, the barb of the other fastening part is inserted intothis opening. Due to the approach of the two fastening parts, themagnetic force begins to act between the two fastening parts. Thereforethe two fastening parts are pulled toward one another. It is preferablefor the magnetic force to increase as the distance between the fasteningparts is reduced. Due to the curved design of the opening of thefastening parts, the barbs are guided along the curved inside surface ofthe opening. The barb thus automatically enters the holding device ofthe barb on the other fastening part so that, in addition to thefastening effect, which is based on the magnetic force, a securemechanical closure of the jewelry clasp is also ensured.

In another preferred embodiment of the invention, the housing for thefastening parts has an identical number of barbs and holding devices. Itis preferable for each fastening part to have two barbs and two holdingdevices. The number 2 is especially preferred because this permits asymmetrical arrangement of the barbs and holding devices relative to oneanother and there is still enough space between the barbs for the twoclosure parts to approach one another and for the barb of one fasteningpart to be guided into its closing position by the corresponding designof the opening of the other fastening part. It has been found that ajewelry clasp, in which the fastening parts each have two barbs and twoholding devices, ensures a particularly effective and secure closure.

In addition, the use of two barbs and two holding devices permits adelicate and visually attractive design of the fastening parts. Inaddition, due to the delicate design of the fastening parts, this saveson material, so that inexpensive production of the fastening partsaccording to the invention is possible.

In another preferred specific embodiment of the invention, the permanentmagnets are situated in the interior of the fastening parts. Thepermanent magnets are also advantageously designed to be cylindrical andhave diameters which correspond to the inside diameters of the housingsof the fastening parts. In the sense of the present invention, the term“correspond” means that the permanent magnets can be inserted into thecylindrical housing of the fastening parts without forming a visuallyperceptible distance from the interior side of the housing and withoutpermitting any play in the permanent magnet or wobbling. The permanentmagnets are advantageously accommodated by the lower area of thefastening parts and protrude into the upper area of the fastening parts.

In another preferred embodiment of the invention, the permanent magnetsare of different lengths. One of the two permanent magnetsadvantageously has a length which preferably amounts to 50% to 70%,especially preferably 55% to 65% and most preferably 58% to 62% of thetotal height of the fastening part, measured from the lower base plateof the fastening part. This permanent magnet advantageously protrudespreferably 20% to 40%, especially preferably 25% to 35% and mostpreferably 28% to 32% into the upper area of the fastening part. It isadditionally preferred for the permanent magnet of the other fasteningpart to have a height which preferably amounts to 70% to 95%, especiallypreferably 75% to 90% and most preferably 80% to 85% of the total heightof the fastening part. This second permanent magnet preferably protrudes60% to 80%, especially preferably 65% to 75% and most especially 68% to72% into the upper area of the fastening part. It is preferable for thesum of the lengths of the permanent magnets protruding into the upperpart of the fastening parts to correspond together to the height of theupper area of the fastening part. The different lengths of the permanentmagnets are illustrated in a particularly illustrative manner in FIGS. 3to 5 of the present patent application. The aforementioned dimensionsadvantageously produce the surprisingly effective interaction of themechanical and magnetic closing effect of the jewelry clasp according tothe invention, which goes beyond the sum of the individual effects.

In another preferred specific embodiment of the invention, the permanentmagnets are made of neodymium. Neodymium is one of the metals of therare earths and is advantageously used for particularly strong magnets.It may also be preferable to use a neodymium-iron-boron compound forproduction of the permanent magnets. Neodymium advantageously has apermanent magnetic behavior with a susceptibility χ of 3.6×10⁻³.Neodymium magnets are surrounded by an especially strong magnetic fieldwhich permits a secure magnetic fastening of the jewelry clasp accordingto the invention. When combined with other materials, these magnetsconstitute an inexpensive opportunity to create a large magnetic forceat a reasonable price.

In another preferred embodiment, one fastening part has a larger insidediameter than the other fastening part. The different sized insidediameters of the two fastening parts together with the curved design ofthe opening of the two fastening parts advantageously make it possiblefor the barbs of one fastening part to fit precisely into the holdingdevices of the other fastening part. In the sense of this invention, thecurved design of the opening of the two fastening parts is also referredto as a “screw-like structure.” Due to this screw-like structure of thefastening parts, the angle of rotation at which the openings in the twofastening parts encounter one another advantageously does not play arole. The magnetic force and the design of the opening ensure that thebarbs and holding devices will always be in the preferred closingpositions.

It has been found that fastening parts in the stated height range ensurea particularly good handling. On the one hand, the fastening partsaccording to the invention can be gripped easily and brought intocontact with one another. On the other hand, they produce ahigh-quality, visually pleasing, delicate impression in the user and theobserver, which in particular does not give a clumsy impression.

In another preferred embodiment of the invention, the height of thefastening parts is in the range of preferably 9 to 11 mm, especiallypreferably 9.95 to 10.05 mm, most preferably 10 mm, and the fasteningparts preferably have an outside diameter of 4 to 8 mm, especiallypreferably 5 to 7 mm, most preferably 6 mm, and the fastening partpreferably has an inside diameter of 4 to 4.5 mm, most preferably of 4.2mm, and the fastening part preferably has an inside diameter of 3.8 to4.1 mm, most preferably of 4.0 mm. It has proven advantageous to designthe fastening parts with inside diameters and outside diameters withinthe aforementioned ranges because this permits a particularly simple andsecure joining of the fastening parts. This simplifies handling of thejewelry clasp according to the invention and prevents unwantedentanglement and blocking of the fastening parts. It has advantageouslybeen found that, when using outside diameters in the range of 5 to 7 mm,a surprisingly low-friction engagement of the fastening parts is madepossible. In addition to the advantageous effects mentioned above, apreferred outside diameter of 6 mm results in a particularly easyconnection to a sheathing of the fastening parts being made available,and this sheathing can be secured on the fastening parts in aparticularly effective manner.

It has been found that fastening parts in the preferred height rangeensure a particularly good handling. On the one hand, the fasteningparts according to the invention can be gripped well and can be broughtinto contact with one another. On the other hand, fastening parts give adelicate, visually attractive and high-quality impression to the userand observer, and this impression does not make them appear to be chunkyand bulky in particular.

It has also been found that fastening parts with a preferred height of 9to 11 mm can be manufactured especially easily and inexpensively becausethese dimensions correspond especially well to those of standardizedmilling machines and casting devices. A preferred height of thefastening parts of 9.95 to 10.05 mm is advantageous in particular when aparticularly delicate and visually slender appearance of the jewelryclasp is to be achieved. Tests have shown in this regard that at apreferred height of the fastening parts, such a ratio relative to theoutside diameter of the fastening parts is achieved that it gives avisually pleasant positive impression in most observers. A preferredheight of the fastening parts of 10 mm corresponds surprisinglywell—both visually and technically—to the usual dimensions and standardsin the technical field of jewelry production, so that such fasteningparts can be connected to the connecting ends of the pieces of jewelryin a particularly simple and visually attractive manner. For example,the fastener device according to the aforementioned embodiment of theinvention may also be used to join different elements of clothing itemsto one another. Bikini tops or halter neck tops might be one example.

In another preferred embodiment of the invention, the height of thefastening parts is in the range of preferably 4 to 6 mm, especiallypreferably 4.5 to 5.5 mm, most preferably 5 mm, and the fastening partspreferably have an outside diameter of 2 to 4 mm, especially preferably2.5 to 3.5 mm, most preferably 3 mm, and the fastening part preferablyhas an inside diameter of 2 to 2.25 mm, most preferably 2.1 mm and thefastening part preferably has an inside diameter of 1.9 to 2.05 mm, mostpreferably 2.0 mm. These dimensions advantageously and preferably eachcorrespond to 50% of the values already cited in the precedingembodiment with regard to the height and inside diameter and outsidediameter. The advantages mentioned above with regard to the individualdimension ranges thus also apply similarly to the 50% reduced values.The reduced embodiment may be particularly easy to use for children'spieces of jewelry in which opening of the jewelry clasp is particularlyundesirable because it could result in the jewelry being swallowed, forexample. In addition, pieces of jewelry for children are often designedto be particularly small, which is also true of the fasteners for themso that they are suitable for small children's hands. Material isadvantageously saved through this design of the jewelry clasp, so thatresources are conserved and manufacturing costs are reduced. Thisembodiment is therefore particularly advantageous for jewelry claspsmade of high-quality and expensive materials.

In another embodiment of the invention, the height of the fasteningparts is preferably in the range of 10 to 30 mm, especially preferably15 to 25 mm, most preferably 20 mm, and the fastening parts preferablyhave an outside diameter of 5 to 15 mm, especially preferably 6 to 13mm, most preferably 12 mm preferably has an inside diameter of 5 to 10mm, most preferably 8.4 mm, and the fastening part preferably has aninside diameter of 6 to 10 mm, most preferably of 8 mm. It has beenfound that the aforementioned dimensions are especially suitable forproviding a fastener device for industrial applications in particular,for example, for mountain climber cables, dog leashes and/or cablecouplings, but this list should show only possible applications and isnot intended to be definitive. For example, carabiner hook-and-screwconnections, which are subject to the disadvantages and shortcomingsdescribed in the description of the prior art, could advantageously bereplaced by fastener devices according to the invention. The fastenerdevice according to the invention thus facilitates the joining ofdifferent cables or cords and ensures a particularly secure connection.For example, the fastener device may also be used to join components ofclothing items to one another.

There is a need for reliable closing of jewelry clasps, so that thejewelry is not lost. On the other hand, there is an expectation on thepart of consumers that a piece of jewelry should be easy to open andclose, i.e., it should be easy to handle. These two requirements arecontradictory to a certain extent because known jewelry clasps that areeasy to open and/or those that are known from the prior art do notgenerally ensure a secure fastening, and furthermore, secure fasteningmechanisms are typically difficult to handle. The present inventionsurprisingly overcomes this presumed contradiction and thus constitutesa departure from the prior art.

In another preferred embodiment of the invention, the barbs of afastening part protrude further into the holding devices of thecorresponding fastening part when there is a pull along the imaginaryaxis of opening and closing which runs centrally in the fastening parts.When there is a sudden strong and abrupt pull on the two fastening partsalong the imaginary axis of opening and closing, the adhesive connectionof the two permanent magnets in the interior of the fastening parts maybe released. The barb of one fastening part is advantageously secured bythe holding device on the other fastening part.

The fastening effect of the jewelry clasp according to the invention isadvantageously based on two supplementary principles: the barbs andholding devices ensure a mechanical closure of the jewelry clasp whilethe two permanent magnets in the interior of the fastening parts make amagnetic contribution toward a secure fastening of the jewelry clasp. Ifthe two fastener components are eliminated, for example, due to a suddenpull, then one of the two components of the closing mechanism alone canalso ensure an effective fastening of the jewelry clasp. The jewelryclasp according to the invention is thus a particularly efficient safetymechanism against inadvertent opening of the jewelry clasp with a suddenpull. When the pull is released, i.e., when the magnetic force betweenthe two permanent magnets is greater than the tensile force pulling thetwo fastening parts apart from one another, the two fastening parts arepulled back together again by the magnetic force until they are in theoriginal closing position in a form-fitting manner. It was completelysurprising that the sliding surfaces in particular which are preferablyformed by the flat regions between the holding device and thetransitional area between the first area and the second area of thefastening part, this attraction is supported in a particularly effectivemanner. Use tests have shown that the design of the sliding surfacesmakes a significant contribution to the synergistic cooperation of themechanical closing effect with the magnetic closing effect of thejewelry clasp, wherein the overall fastening effect goes surprisinglybeyond the fastening effect of a strict aggregation of closing effects.In addition, the presence of the sliding surface preferably leads to afastener that is particularly easy to handle and can be operatedespecially well with one hand in particular.

The unexpectedly effective cooperation of the mechanical components withthe magnetic components of the jewelry clasp according to the inventionis manifested in particular when applying an axial pull in the directionof the imaginary axis of opening and closing. The overall closing effectof the mechanical effects and the magnetic closing effects then does notin particular amount to a strict aggregation of the known individualeffects but instead has a synergistic effect in particular which ismanifested in that the fastening parts of the jewelry clasp according tothe invention can withstand greater loads than the usual jewelry claspsand fastener devices whereas these loads are greater in particular thanthe sum of the load that can be withstood by a jewelry clasp which isbased only on mechanics or only on magnetism. The present patentapplication advantageously does not maximize exclusively the fastenereffect of the jewelry clasp but instead optimizes its overallfunctionality to the extent that a surprisingly good balance is assuredbetween a secure fastening on the one hand and a fastener that is easyto handle on the other hand.

In another preferred embodiment of the invention, the jewelry clasp isopened and closed by rotating the two fastening parts in oppositedirections from one another. To close the jewelry clasp, a barb of afastening part is advantageously inserted first into one of the twoopenings in the corresponding fastening part. The barb of the onefastening part is advantageously moved by the magnetic force along theinside wall of the opening and into one of the holding devices of thecorresponding fastening part due to the curved screw-like or thread-likedesign of the opening of the fastening parts.

Due to the curved design of the opening of the fastening parts, the twofastening parts are rotated one into the other until the two permanentmagnets are in form-fitting contact in the interior of the fastener. Atthe end of the rotating process, both the mechanical component and themagnetic component are contributing toward an unexpectedly securefastening of the jewelry clasp which is the result of the synergisticinteraction of the different closing effects. It is preferable for thetwo fastening parts to move in opposite directions in the rotatingoperation. The magnetic attraction of the two permanent magnetspreferably results in the barbs sliding around the sliding surfaces,which preferably form an angle α of greater than or equal to 25° withthe imaginary axis of opening and closing, in particular in africtionless manner and without any entanglement or clamping into theholding devices of the corresponding fastening part.

It is additionally preferred for the first areas of the fastening partsto each have six to ten bulges, preferably eight wedge-shaped bulges,such that half of the bulges are present on the inside of the housingwall of the fastening parts and the other half are in the same locationon the housing wall on the outside of the fastening parts. Thesewedge-shaped bulges are illustrated in FIG. 4. In the context of thispatent application, a wedge is a three-dimensional structure having arectangular base area formed by two parallel longitudinal sides and widesides and having a height that changes over the length of the wedge. Theincrease in height runs in a linear and steady pattern from the lowestheight, which is usually h=0 mm, to the maximum height. Thesewedge-shaped bulges facilitate the fixation of the permanent magnet whenthey are mounted on the inside of the housing wall, and thereby increasethe stability of the fastening parts when they are mounted on theoutside of the housing wall. It was completely surprising that thehandling of the fastening parts of the jewelry clasp according to theinvention can be greatly facilitated by providing wedge-shaped recesses.

In another preferred embodiment, the wedge-shaped bulges are distributedregularly over the circumference of the housing wall of the fasteningparts. When four bulges, for example, are provided on the inside oroutside of the housing wall, these four bulges each have an anglespacing of 90°. The average person skilled in the art will recognizethat the angular distance beta can preferably be determined by thefollowing equation with a number n of n wedge-shaped bulges:

beta=360°/n.

Due to the regular distribution of the wedge-shaped bulges on thecircumference of the housing wall of the first areas of the fasteningparts, a visually attractive and especially harmonious impression of thefastening parts is surprisingly achieved. The average person skilled inthe art knows that the angle or distances determined in this way areaverage values, but the actual distances may deviate from the calculatedaverage, for example, due to deviations in production. Of course jewelryclasps having such deviating values still fall within the scope ofprotection of the present invention.

It is additionally preferable for the wedge-shaped bulges to have alength in the range of 2.2 to 2.6 cm, preferably a length of 2.4 cm.When the wedge-shaped bulges have a length in the range of 2.2 to 2.6 cmpreferably a length of 2.4 cm, it is advantageously possible to arrangethem in the position of the first areas on the inside and outside of thefastening parts, among others, on which the housing wall has the leastheight.

It is additionally preferable for the wedge-shaped bulges to taper fromthe top to the bottom. In the context of the present patent application,the term “bottom” refers to the direction in space in which the rearside of the fastening part is arranged. However, the term “top”describes the direction in space in which the second areas of thefastening part, comprising the barbs of the fastening part, among otherthings, are arranged. Thus the wedge-shaped bulges have their maximumheight in the area of the rear side of the fastening parts and on theiropposite ends.

In other preferred specific embodiment, the invention relates to ajewelry clasp with wedge-shaped bulges on fastening part A having amaximum height in the range of 0.19 to 0.21 mm, preferably a height of0.2 mm. It is further preferred that the wedge-shaped bulges onfastening part B arranged on the inside of the housing wall of fasteningpart B have a maximum height in the range of 0.09 to 0.11 mm, preferablya height of 0.1 mm, and the wedge-shaped bulges on fastening part Barranged on the outside of the housing wall of the fastening part B,have a maximum height in the range of 0.19 to 0.21 mm, preferably aheight of 0.2 mm. Tests have shown that the wedge-shaped bulges havingthe aforementioned dimensions ensure an improved handling in comparisonwith the jewelry clasps known from the prior art, in particular for thecase when a piece of jewelry having a jewelry clasp according to theinvention is to be closed reliably with just one hand, for example,because the bulges offer an improved resistance and point of attack.This is also true with the use of the fastener device according to theinvention for connecting cables, for example, in climbing or mountainclimbing, where one must often use only one hand for joining cable endsand support in bringing together the cable ends through the attractiveforce of the permanent magnets offers an excellent advantage.

In another preferred specific embodiment of the invention, the fasteningparts comprise refined zinc alloys, stainless steel, aluminum, silver,gold, ceramic material, titanium, ABS plastic, glass fiber-reinforcedplastic and/or carbon fibers. It is preferable for the fastening partsto be made of nonmagnetic materials so that there is nosuper-positioning of different magnetic fields that might have anegative effect on the fastening effect of the permanent magnets.

The term “refined zinc alloy” in the sense of the present inventionpreferably refers to zinc alloys that have been standardized with regardto their composition and may contain copper and/or aluminum asadditional alloy ingredients. Refined zinc alloys can be processedadvantageously and more easily than pure zinc and are also available ata lower cost. Refined zinc alloys are preferably processed by zinc diecasting, which preferably refers to a die casting processing. Therefore,large quantities of fastening parts according to the invention can bemanufactured advantageously under inexpensive conditions. The fasteningparts manufactured in this way are characterized by a high dimensionalstability, have very good mechanical values and are very suitable for asurface treatment such as nickel plating or chrome plating. Because oftheir properties, refined zinc alloys are tolerated especially well andusually do not lead to allergic reactions, as tests have shown.Fastening parts produced from refined zinc alloys may thereforeadvantageously also be used in particular for producing jewelry claspsfor children or for people with a tendency to skin reactions.

Stainless steel is characterized by a particularly high degree of puritywith regard to the alloy additives used and usually does not have anyvisual impairment due to rust or corrosion. Fastening parts producedfrom aluminum are advantageously especially lightweight and give avisually attractive impression to the user. Titanium is a transitionmetal characterized by a high corrosion resistance, good strength and alow weight. It advantageously has a silvery metallic appearance. Ceramicmaterials and plastics advantageously do not cause any allergies and arean inexpensive, low-weight alternative to the materials mentioned above.

ABS plastics (acrylonitrile-butadiene-styrene) are preferablythermoplastics, which are very suitable for being coated with metals(galvanization) and polymers. In particular galvanizing, painting andprinting of fastening parts produced from ABS plastic are made possiblein especially simple ways. In addition, it has been found that fasteningparts made of ABS plastic can advantageously also be produced by using3D printing methods.

The term “glass fiber-reinforced plastic” in the sense of the presentinvention preferably denotes a fiber-plastic composite consisting of aplastic and glass fibers. It is preferable to use thermosetting plasticssuch as polyester resin or epoxy resin as the base as well asthermoplastic polymers such as polyamide [nylon]. Glass fiber-reinforcedplastics advantageously form an inexpensive but nevertheless very highquality fiber-plastic composite which can also be used, for example, inapplications that are subject to high mechanical stresses. In comparisonwith fiber-plastic composites made of other reinforcing fibers,glass-fiber-reinforced plastic preferably has a relatively low modulusof elasticity, even lower than that of aluminum, for example. A highelongation at break and elastic energy uptake are advantageouslyachieved due to the glass fiber reinforcement. Tests have shown thatglass fiber-reinforced plastic also has an excellent corrosion behavioreven in an aggressive environment, which is why it is especiallysuitable for manufacturing fastening parts for pieces of jewelry. Inaddition, glass fiber-reinforced plastics are characterized by goodmoldability and a high design freedom in the production of fasteningparts.

The terms “carbon fiber” and “carbon fiber-reinforced plastic” in thesense of the present invention preferably denote a composite material,in which carbon fibers are embedded in a plastic matrix, usually epoxyresin. The matrix material preferably serves to bond the fibers and tofill the interspaces. The matrix of carbon advantageously improves themechanical properties of the material, in particular the tensilestrength and stiffness. An important advantage when using carbon fibersis the low density of the material in comparison with metal so thatespecially lightweight fastening parts can be obtained when they areproduced from carbon fibers.

When gold is used as the starting material for production of thefastening parts, it is preferable to use gold with a degree of purity ofless than 14 karat. This preferably corresponds to an amount of 585parts by weight gold in a total amount of 1000 parts by weight.Especially high-quality and high-priced fastening parts are obtained byusing gold.

In another preferred specific embodiment of the invention, the fasteningparts are produced by milling, by CNC milling, by the injection moldingprocess and/or by the die-casting method.

The term “milling” in the sense of the present invention preferablydenotes the machining of metals, wood or plastics in such a way thatthey are cut by means of a milling tool. This is preferably performed onspecial machine tools, whereby in the context of the present invention,the term preferably denotes manually or mechanically controlled milling,which is preferably also referred to as conventional milling. It ispreferable that the rate of advance in conventional milling isoptionally regulated with cranks or simple machine-feed systems.However, the term CNC milling denotes computer-controlled milling, inwhich the milling machine can be programmed by means of a machinecontrol. The CNC technique advantageously enables 3D milling, with whichcomplex 3D contours can be created.

The term “injection molding method” in the sense of the presentinvention preferably denotes to a casting method, which is used mainlyin processing plastics. It is preferable for the respective material tobe liquefied, i.e., plasticized, in an injection molding machine andthen injected under pressure into a mold, which is the injection mold.In the mold, the material is converted back to the solid state,preferably by cooling or by a crosslinking reaction, and then is removedas a finished part after opening the mold. The cavity of the moldadvantageously determines the shape and surface structure of thefinished part. It has been found that directly usable molded parts canbe produced inexpensively in large numbers with this method. Inaddition, injection molding permits almost free choice of shape andsurface structure such as, for example, smooth surfaces, a grain forareas, patterns, engravings, etc., that are pleasant to touch, and coloreffects.

The term “die casting” describes an industrial casting method for serialor mass production of construction parts. It is especially suitable formetallic materials with a low melting point such as, for example, alloysof aluminum, zinc, silicon and/or magnesium. It is preferable for theliquid melt to be forced under a high pressure of approx. 10 to 200 MPaand at a very high mold filling rate of up to 12 m/s into a die-castingmold, which is preferably also referred to as a casting mold or cavityin the sense of the present invention, where it preferably solidifies indie casting. It is advantageous to work without a model and/or permanentmold in the die-casting method, so that the mold need only bemanufactured once, which is advantageous in mass production of the samefastening parts.

In another preferred specific embodiment, one of the two fastening partsis provided with a sheathing of nonmagnetic stainless steel, aluminum,ceramic material, titanium, plastic and/or a noble metal. It ispreferable for the noble metals to be selected from a group consistingof gold, silver, platinum, iridium, palladium, osmium, rhodium,ruthenium and/or a combination of these noble metals. This sheathing isadvantageously provided with a product identification or brand nameidentification. The sheathing of noble metals or the other materialslisted above upgrades the visual appearance of the fastening parts andcreates a high-quality attractive visual impression of the jewelry claspaccording to the invention.

In another preferred specific embodiment of the invention, the sheathingof one of the two fastening parts is affixed by hydraulic pressing.Hydraulic presses operate by the hydrostatic principle in a force-boundprocess. According to the hydrostatic principle, the pressure in aliquid is constant and a force acting on a wall of a container can thusbe multiplied in this way. As a rule, hydraulic presses are used when avery high pressure is acting constantly and uniformly over a relativelygreat distance for the purpose of compression. Hydraulic presses canadvantageously be used in a flexible manner and are easy to retrofit. Itis also preferable for the fixation of the permanent magnets in thefastening parts to be accomplished by hydraulic pressing. However, itmay also be preferable to implement the fixation of the permanentmagnets in the fastening parts by adhesive bonding. These two methodsmay also be combined with one another to advantage. This ensures aparticularly effective fixation of the permanent magnets in thefastening parts.

In another aspect, the invention relates to the use of the jewelry claspas a safety clasp and/or fastening system. It is therefore alsopreferable to refer to the jewelry clasp according to the invention as afastening device, wherein the two terms are used synonymously in thecontext of the present invention. Use of the fastening device as asafety fastener and/or fastening system advantageously relates toindustrial applications such as mountain climbing cables, dog leashesand/or cable couplings, but this list should merely show possible fieldsof application and should not be conclusive. It was completelysurprising and in particular was not self-evident that the jewelry claspaccording to the invention could also be used in industrialapplications. In the past, the average person skilled in the art hasassumed that jewelry clasps may be used primarily for accessories andpieces of jewelry, which can be attributed in particular to theshortcomings and disadvantages described in the prior art. Due to thesynergistic combination of mechanical and magnetic closing effects andthe resulting unexpected overall closing effect of the fastening deviceaccording to the invention, this can now also withstand loads such asthose not previously assumed in the technical world, namely that thesewould be too great for conventional jewelry clasps and fastening devicesof the aforementioned type. The jewelry clasp according to the inventionand/or the inventing fastening device can surprisingly now also be usedin novel application areas that could not previously be imagined, wherethese industrial applications would not have been self-evident for theaverage person skilled in the art in particular.

In another aspect, the invention relates to a bracelet comprising ajewelry clasp according to the invention. In another aspect, theinvention relates to a kit comprising at least two bracelets which havea jewelry clasp according to the invention and are joined to one anotherin such a way as to form a decorative necklace. It has been found thatthe average diameter of the human arm is in a ratio to the averagediameter of the human neck such that a necklace can be formed by joiningat least two bracelets to one another and together forming a necklace.Depending on the desired length of the necklace and depending on thepreferred method of wearing it, two, three or four bracelets can becombined with one another to form a necklace by means of the jewelryclasps according to the invention.

In the sense of the present invention a necklace consists of a group ofat least two bracelets wherein it is preferable for the necklace to beat least twice as long as a bracelet. This is the case, for example,when two bracelets are joined together to form one necklace. It may alsobe preferable for the necklace to be at least three or four times longerthan a bracelet. In this case three or four bracelets are advantageouslyjoined to one another to form a necklace.

In another aspect the invention relates to a kit comprising at least twobracelets. It is preferable for these two bracelets to be joined to oneanother by means of the jewelry clasps according to the invention. Thisyields a necklace that is worn close to the neck. Combining threebracelets yields a necklace that is worn more loosely. It may bepreferable to combine similar bracelets to form a necklace but it mayequally be preferable to combine different bracelets. When using morethan two bracelets it may also be preferable to combine two similarbracelets and one different bracelet or the other way around. Thus thereare no limits to the possible variations.

It is preferable to provide bracelets in lengths of 8, 20 and 22 cm, forexample. To increase the multitude of variations and in particular alsoto make it possible to assemble long necklaces by combining them,bracelets are also provided in the preferred lengths of 26 and 75 cm,for example. These are made preferably essentially of leather and may beused as wrap-around bracelets. The average person skilled in the artwill understand that the term “essentially” in the context of thispatent application is to be understood to mean that the bracelets havingpreferred lengths of 26 and 75 cm are made primarily of leather but mayalso include smaller amounts of other materials, preferably naturalmaterials. The use of leather and other natural materials has proven tobe particularly advantageous when users of the bracelets and necklacessuffer from allergies to metals or metal alloys.

It may also be preferable for the kit to comprise at least twobracelets, wherein the at least two bracelets are joined to one anotherusing other types of jewelry clasps. Within one kit, several types offasteners may advantageously be combined with one another in differentpositions.

The invention will now be described in greater detail on the basis ofexemplary embodiment and the following figures, in which:

FIG. 1 shows a side view and oblique view of fastening parts A and Baccording to the invention

FIG. 2 shows an enlarged side view of one each of fastening parts A andB according to the invention

FIG. 3 shows an exemplary side view of a fastening part A according tothe invention with an imaginary axis of opening and closing

FIG. 4 shows an example of a side view of a fastening part B accordingto the invention, also showing the first and second areas

FIG. 5 shows additional side views of one fastening part A and B eachaccording to the invention

FIG. 6 shows a top view of a fastening part A and B according to theinvention

FIG. 7 shows a schematic diagram of how bracelets are worn on a humanarm

FIG. 8 shows a schematic diagram of three bracelets

FIG. 9 shows a schematic diagram of how a necklace is worn on a humanneck

FIG. 10 shows a schematic diagram of a necklace according to theinvention, comprised of three bracelets

FIG. 11 shows a schematic diagram of a necklace according to theinvention, comprised of two bracelets

FIG. 1 shows a side view and an oblique view of the fastening parts Aand B according to the invention. The top part of FIG. 1 shows anoblique view of the two fastening parts A and B according to theinvention. This shows the permanent magnets (10) in the interiorregion//internal area? of a fastening part (28). The permanent magnets(10) are affixed in the internal area//interior region? (28) of thefastening parts (A, B) by means of hydraulic pressing or adhesivebonding. The fastening parts (A, B) consist of a housing (12), the rearside (16) of which faces the piece of jewelry. The housing (12) isdivided into a first area (18) and a second area (20), the first area(18) being the lower area of the cylindrical housing (12). The secondarea or upper area (20) of the fastening part (A or B) is designed to beopen (14) and is formed by barbs (22) and holding devices (24). Thesebarbs (22) and holding devices (24) are designed to be complementary toanother and thus cooperate with one another in such a way that theyensure a secure fastening of the jewelry clasps.

FIG. 1 shows clearly that the permanent magnets (10) of the fasteningparts (A, B) have different lengths. The permanent magnet (10) of thefastening part (A) is designed to be longer than the permanent magnet(10) of the fastening part (B) and it protrudes further into the secondarea (20) of the fastening part (A).

FIG. 1 additionally shows the curved shape of the intermediate spacebetween the barbs (22) of the fastening parts (A, B). This curved shapeof the interspaces facilitates closing of the jewelry clasps accordingto the invention due to the fact that when bringing the two fasteningparts (A, B) into contact, the barbs (22) of the one fastening part (A)entered the interspaces situated between the barbs of the fastening part(B) and are guided along the curved shape of the intermediate space intothe holding device (24) of the fastening part (B). The attractivemagnetic force between the two permanent magnets (10) of the twofastening parts (A, B) plays a supporting role here.

Due to the combination of the mechanical design of the upper area of thehousing of the fastening parts (A, B) with the use of magnetic forcebetween the two permanent magnets (10) of the two fastening parts (A,B), a secure fastening of the jewelry clasps is ensured. In particularit is possible to close the jewelry clasps by said combination usingjust one hand.

FIG. 2 shows an enlarged side view of one each of the fastening parts (Aand B) according to the invention. FIG. 2 shows clearly the differencein length of the permanent magnets (10). The permanent magnets (10) aresituated in the internal area (28) of the respective fastening part. Thefastening part (A or B) is formed by a housing (12) which is itselfformed by a rear side (16) and an exterior wall (26) in the lower area(18). The housing (12) is designed to be cylindrical or sleeve-shaped inthe lower area (18). Fastening mechanisms may be provided on the rearside (16), with which attachment of the jewelry clasp to a piece ofjewelry can be implemented. The upper area (20) of the fastening part (Aor B) is formed by barbs (22) and holding devices (24). This shows thatthe holding devices (24) represent a recess on the lower side of thebarb (22). There is an opening (14) in the fastening parts (A, B)between the barbs.

FIG. 3 shows an example of a side view of a fastening part (A or B)according to the invention with an imaginary axis (30) of opening andclosing. This imaginary axis (30) of opening and closing of thefastening parts (A or B) runs centrally, i.e., in the middle through thelower area (18) of the fastening part, which is designed to becylindrical and continues in a straight line in the upper area (20) ofthe fastening part (A or B). The imaginary axis (30) of opening andclosing thus starts at the midpoint of the circular rear side (16) ofthe housing (12) of the fastening part (A or B) and then leads upward ata right angle to said rear side (16). The imaginary axis (30) of openingand closing thus forms an imaginary midline for both the housing (12) ofthe fastening part and for the permanent magnets (10).

The adhesive bond formed in the closing position between the twopermanent magnets (10) in the interior (28) of the housing (12) isreleased when there is a sufficiently strong pull (mainly suddenly orwith a jerk) on the two fastening parts (A, B) along the imaginary axis(30) of opening and closing. Despite this release of the bond based onmagnetic force, the barbs (22) of the one fastening parts (A or B)remain in the holding devices (24) of the other fastening part (B or A)respectively. When the pull subsides, the permanent magnets (10) arepulled toward one another again, and the jewelry clasps again assume theoriginal completely closed position, in which the permanent magnets (10)are in form-fitting contact with one another.

In addition, FIG. 3 shows a sliding surface (52) which forms an angle α(54) with the imaginary axis (30) of opening and closing. This angle α(54) may be imagined as being formed in particular when a straight line(56) is drawn in the plane spanned by the sliding surface (52). All thepoints on this straight line (56) lie in the plane of the slidingsurface (52). The angle α (54) is preferably greater than or equal to25°.

As an example FIG. 3 shows a fastening part (A) which can be seen by thefact that the permanent magnet (10) of the fastening part (A) shown hereprotrudes into the area of the barbs (22). The permanent magnet (10) ofthe fastening part (A) therefore protrudes further into the second part(20) of the fastening part (A).

FIG. 4 shows an example of a side view of a fastening part (B) accordingto the invention with the diagram of the first area (18) and the secondarea (20). FIG. 4 shows a fastening part (B), which can be recognized bythe fact that the permanent magnet (10) takes up only approximatelyone-third of the total length of the second area (20) of the fasteningpart (B).

The first area (18) of the fastening part (B) extends from the rear side(16) of the housing (12) of the fastening part (B) up to the locationwhere the completely closed exterior wall (26) of the housing (12) endsand an intermediate space begins between the barbs (22) of the secondarea (20) of the fastening part (B), by definition, the transitionbetween the first area (18) and the second area (20) of the fasteningpart (B) is marked with a dotted line in FIG. 4.

In addition, FIG. 4 shows one possible position for a wedge-shaped bulge(50) on the outside of the housing wall (12, 26) of the first area (18)of a fastening part (A, B). The rectangular base area of thewedge-shaped bulge (50), which is bordered by two parallel longitudinalsides and two parallel broad sides can be seen in the top view. Theheight of the wedge (50), which increases from the bottom to the top,extends in the third direction in space, which is not shown here. Thismeans that the height of the wedge (50) assumes its smallest value inthe area of the rear side (16) of the fastening part, whereas the heightof the wedge (50) assumes its maximum value on the opposite side of thewedge-shaped bulge (50). The wedge-shaped bulge (50) tapers from top tobottom.

This does not show that the wedge-shaped bulges (50) are arrangeduniformly or regularly over the circumference of the outside and insidewalls of the housing (12) of the first area (18) of the fastening part(A, B). A uniform or regular arrangement of the wedge-shaped bulges (50)means in particular that the angular distances between the wedge-shapedbulges (50) are constant. For example, in the presence of four bulges onthe inside or outside of the housing (12), the angular distance is360°/4=90°. In general, the angular distance β (beta) in degrees isbetween n individual wedge-shaped bulges according to the formula360°/n=beta.

FIG. 5 shows another side view of one each of the fastening parts (A orB) according to the invention. In comparison with FIG. 2, the fasteningparts (A, B) are rotated by an angle α here. FIG. 5 shows clearly thatthe permanent magnet (10) of the fastening part (B) is designed to beshorter than the permanent magnet (10) of the fastening part (A). FIG. 5also shows that the permanent magnet (10) is situated in the interior(28) of the fastening parts (A, B) and that their diameters (34, 36)correspond to the inside diameters of the housings (12) of the fasteningparts (A, B). The housings (12) are formed by an outside wall (26) andthe rear side (16) and are designed to be cylindrical or sleeve-shaped.The rear side (16) has a circular base area. For visual reasons, thehousing (12) may be provided with a sheathing (32). This sheathing (32)may consist of nonmagnetic stainless steel, aluminum, ceramic material,titanium, plastic and/or noble metals.

In addition, FIG. 5 also shows the barbs (22) and the holding devices(24) of the fastening parts (A, B). FIG. 5 also shows the opening (14)in the upper area (20) of the fastening part. The barbs (22) of the onefastening part (A or B) are inserted into these openings (14) in theinterspaces between the barbs (22) of the respective other fasteningpart (B or A). the jewelry clasp according to the invention is closed ina closing position (48) because of the magnetic force between the twopermanent magnets (10) and the curved design of the transitional areabetween the first area (18) and the second area (20) of the fasteningpart (A, B), along the exterior wall of which the barb (22) of the onefastening part (A or B) is guided to the holding device (24) of theother fastening part (B or A).

FIG. 6 sows the top view of the two fastening parts (A and B). Theinside diameter (36) of the opening (14) of the fastening part (B) issmaller than the inside diameter (34) of the opening (14) of thefastening part (A). Due to the screw-like structure of the upper area(20) of the fastening parts (A, B) the fastening parts (A, B) always fittogether accurately. The thread-like structure created in the twoopenings (14) results in the two fastening parts (A, B) being able to bescrewed together until the two permanent magnets (10) come intoform-fitting contact in the interior (28) of the jewelry clasp.

FIG. 7 shows a schematic diagram of how the bracelets (42 a, b, c)according to the invention are worn on a human arm (38). This shows ahuman arm (38) with a hand (40). The bracelets (42 a, b, c) shown hereare worn in the area of the forearm or the wrist. Similar bracelets ordifferent bracelets may be worn together. It is also possible for two ofthe three bracelets to be identical. Of course it is equally possible towear one, two or several bracelets at the same time. The position of thebracelets is indicated only schematically in FIG. 7 and in practice maydeviate from the diagram shown here.

FIG. 8 shows a schematic diagram of three bracelets (42 a, b, c). Inthis schematic diagram, the round dots at the ends of the bracelets (42a, b, c) correspond to the fastening parts (A. B) of the jewelry claspaccording to the invention. This shows bracelets in an open position,i.e., the fastening parts (A, B) are not in the closed position butinstead are not in contact with one another at all and are separate fromone another.

FIG. 9 shows a schematic diagram of how a necklace (44) is worn on ahuman neck (46). This shows how a necklace (44) is formed by connectingthree bracelets (42 a, b, c). For example, one fastening part (A) of abracelet (42 a) is connected to a fastening part (B) of another bracelet(42 b). Unlike the situation in establishing a closing position of abracelet (42), in which the fastening part (A, B) of a bracelet (42) arebrought together into a closing position, in the case when a necklace(44) is to be formed from two or more bracelets, corresponding fasteningpart (A, B) of different bracelets (42) are brought into contact withone another and brought to a closing position. Depending on how manybracelets (42) are to be combined with one another to form a necklace(44), the length of the necklace (44) is approximately two, three orfour times as long as the bracelet (42), etc.

A kit comprised of at least two bracelets joined together to form anecklace (44) may thus comprise bracelets (42) having a jewelry claspaccording to the invention as well as bracelets having a different typeof fastener mechanism as long as the bracelets can be joined together inthe manner described here.

FIG. 10 shows a schematic diagram of a necklace (44) according to theinvention comprises of three bracelets (42 a, b, c). The black dots inFIG. 10 represent the fastening parts (A, B) of a bracelet (42). Thisshows that one fastening part (A) of a bracelet (42) cooperates with acorresponding fastening part (B) of another bracelet (42) to form acomplete closed jewelry clasp. The diagram of three bracelets (42 a, b,c) is shown as an example. It is also possible to combine two, three,four or more bracelets (42) together to form a necklace (42). When anecklace (44) is formed by combining three bracelets (42) the result isa necklace (44) whose length is approximately three times greater thanthe length of a single bracelet (42).

FIG. 11 shows a schematic diagram of a necklace (44) according to theinvention, comprised of two bracelets (42). The black dots correspond tothe fastening parts (A, B), which are in an unconnected, not closedposition in FIG. 11. When a necklace (44) comprised of two bracelets(42) is formed by combining two bracelets (42), the result is a necklace(44) approximately twice as long as single bracelet (42). In thearrangement illustrated in FIG. 11, one fastening part (A) of a bracelet(A or B) cooperates with a corresponding fastening part (B) on the otherbracelet (B or A). The jewelry clasp according to the invention here isused not only for the fastening of the necklace (44) but also serves tojoin the components of the necklace (44), namely the at least twobracelets (42). The necklace (44) formed by combining two bracelets (42)is advantageously worn on the neck with a close fit.

LIST OF REFERENCE NUMERALS

-   A Fastening part-   B Fastening part-   10 Permanent magnets-   12 Housing-   14 Opening-   16 Rear side-   18 First area of a fastening part-   20 Second area of a fastening part-   22 Barb-   24 Holding device-   26 Exterior wall-   28 Interior area of a fastening part-   30 Imaginary axis of opening and closing of the fastening parts-   32 Sheathing-   34 Inside diameter of fastening part A-   36 Inside diameter of fastening part B-   38 Human arm-   40 Human hand-   42 Bracelet-   42 a, b, c Bracelets-   44 Necklace-   46 Human neck-   48 Jewelry clasp in a closing position-   50 Wedge-shaped bulges-   52 Sliding surfaces-   54 Angle α-   56 Straight line in the plane of the sliding surface

1. A jewelry clasp having two fastening parts (A, B), each comprising apermanent magnet and a housing, wherein the housing has an opening and arear side opposite the opening, wherein the housing comprises acylindrical first area and a second area, wherein the second areas ofthe fastening parts (A, B) each comprises mutually complimentary barbsand holding devices and wherein the jewelry clasps may be opened andclosed in a closing position wherein one barb of a fastening part (A orB) is introduced in the closing position into a holding device of theother fastening part (B or A), and the permanent magnets are in contactwith one another.
 2. The jewelry clasp according to claim 1, wherein thesecond areas of the fastening parts (A, B) comprise sliding surfaceswhich form an angle α with an imaginary axis of opening and closingrunning centrally in the fastening parts (A, B).
 3. The jewelry claspaccording to claim 2, wherein the angle α is greater than or equal to25°.
 4. The jewelry clasp according to claim 1, wherein the housingcomprises a first area with a closed exterior wall which is connected tothe rear side of the fastening parts (A, B), and the barbs and holdingdevices form the second area of the fastening parts (A, B).
 5. Thejewelry clasp according to claim 1, wherein the fastening parts (A, B)each have two barbs and holding devices.
 6. The jewelry clasp accordingto claim 1, wherein the permanent magnets are situated in the interiorof the fastening parts (A, B).
 7. The jewelry clasp according to claim1, wherein the permanent magnets have different lengths and/or are madeof neodymium.
 8. (canceled)
 9. The jewelry clasp according to claim 1,wherein the fastening part (A) has a larger inside diameter than theother fastening part (B).
 10. The jewelry clasp according to claim 1,wherein a height of the fastening parts (A, B) is in the range of 9 to11 mm, 9.95 to 10.05 mm, or is 10 mm, and the fastening parts (A, B)have an outside diameter of 4 to 8 mm, 5 to 7 mm, or 6 mm, and fasteningpart (A) has an inside diameter of 4 to 4.5 mm, or of 4.2 mm andfastening part (B) has an inside diameter of 3.8 to 4.1 mm, or of 4.0mm.
 11. The jewelry clasp according to claim 1, wherein the height ofthe fastening parts (A, B) is in the range of 4 to 6 mm, especiallypreferably 4.5 to 5.5 mm, or 5 mm and the fastening parts (A, B) have anoutside diameter of 2 to 4 mm, 2.5 to 3.5 mm, or 3 mm, and fasteningpart (A) has an inside diameter of 2 to 2.25 mm, or of 2.1 mm andfastening part (B) has an inside diameter of 1.9 mm to 2.05 mm, or of2.0 mm.
 12. The jewelry clasp according to claim 1, wherein the heightof the fastening parts (A, B) is in the range of 10 to 30 mm, 15 to 25mm, or 20 mm and the fastening parts (A, B) have an outside diameter of5 to 15 mm, 6 to 13 mm, or 12 mm, and fastening part (A) has an insidediameter of 5 to 10 mm, or of 8.4 mm and fastening part (B) has aninside diameter of 6 mm to 10 mm, or of 8 mm.
 13. The jewelry claspaccording to claim 1, wherein the barbs of a fastening part (A or B) arepositioned further in the holding devices of the corresponding fasteningpart (B or A) when there is a pull along the imaginary axis (30) ofopening and closing running centrally in the fastening parts (A, B). 14.The jewelry clasp according to claim 1, wherein the opening and closingof the jewelry clasp takes place by rotation of the two fastening parts(A, B) in opposite directions.
 15. The jewelry clasp according to claim1, wherein the fastening parts (A, B) comprise refined zinc alloys,stainless steel, aluminum, silver, gold, ceramic material, titanium, ABSplastic, glass fiber-reinforced plastic and/or carbon fibers.
 16. Thejewelry clasp according to claim 1, wherein the fastening parts (A, B)are produced by milling, by CNC milling, by injection molding and/or bydie casting methods.
 17. The jewelry clasp according to claim 1, whereinone of the two fastening parts (A, B) is provided with a sheathing ofnonmagnetic stainless steel, aluminum, ceramic material, titanium,plastic and/or noble metals.
 18. The jewelry clasp according to claim17, wherein the noble metals are selected from a group consisting ofgold, silver, platinum, iridium, palladium, osmium, rhodium, rutheniumand a combination of these noble metals.
 19. The jewelry clasp accordingto claim 17, wherein the sheathing on one of the two fastening parts (A,B) is affixed by hydraulic pressing.
 20. The jewelry clasp according toclaim 1, wherein the permanent magnets are affixed in the fasteningparts (A, B) by hydraulic pressing or adhesive bonding.
 21. (canceled)22. A method of fastening comprising providing the jewelry claspaccording to claim 9 and using the clasp as a safety fastener and/orfastening system.
 23. A bracelet comprising a jewelry fastener accordingto claim
 1. 24. A kit comprising at least two bracelets according toclaim 23, which are joined to one another in such a way as to form anecklace.